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通过多种试验方法、多种频段对沉积岩、变质岩、火成岩进行干燥和有液体饱和状态的对比试验研究,得出低频时干燥岩石的衰减、色散小,相对饱和岩石而言可以忽略。饱和岩石具有衰减峰,其特征随饱和液体黏性而变化。在声频时,干燥岩石的应力–历史波形与饱和岩石相比差别较大。饱和液体的黏滞作用引起弥散和阻止卸载的后沿缓波,并随黏性增大而增强,体现了黏弹性材料特有的属性。全程σ-ε曲线得到干燥岩石的强度大于饱和岩石,平行层理大于垂直层理的强度,具有各向异性。干燥岩石各向异性很弱,液体促进了饱和岩石各向异性的增强。低饱和度时,模量和波速随饱和度增大而降低;高饱和度时模量又随饱和度增大而增大;中等饱和度时,模量、波速基本不随饱和度变化。用PM模型中微观非经典单元在饱和液体的作用下易于被激活,导致PM空间对角密度增大,非线性增强的变化基本能解释上述试验的结果。液体对岩石非线性弹性行为的这些影响,从长期效应来看将会给重大岩石工程的安全带来隐患,必须引起足够的重视。
Through a variety of test methods, a variety of frequency bands of sedimentary rocks, metamorphic rocks, igneous rock drying and liquid saturated state comparative experimental study shows that low-frequency dry rock attenuation, dispersion is small, relative to saturated rock can be ignored. Saturated rocks have decay peaks and their characteristics vary with the viscosity of the saturated liquid. At audible frequencies, the stress-history waveform of dry rocks is quite different from that of saturated rocks. The viscous effect of saturated liquid causes the trailing edge retardation to disperse and prevent unloading, and increases with the increase of viscosity, which reflects the peculiar properties of viscoelastic material. The σ-ε curve shows that the strength of dry rock is greater than that of saturated rock, and the parallel bedding is larger than the strength of vertical bedding and has anisotropy. The anisotropy of dry rock is weak and the liquid promotes the enhancement of anisotropy of saturated rock. At low saturation, modulus and velocity decrease with increasing saturation; modulus increases with increasing saturation at high saturation; and does not change with saturation at moderate saturation. The microscopic non-classical cells in the PM model can be easily activated under the action of saturated liquid, resulting in an increase of the diagonal density of the PM space. The change of the nonlinear enhancement basically can explain the result of the above experiment. These effects of liquid on the nonlinear elastic behavior of rock will bring hidden dangers to the safety of major rock works from the perspective of long-term effects and must be given sufficient attention.